H11 and H13 steel for piston applications

Abstract

A piston for an internal combustion engine includes a piston body having a crown adjacent a skirt. Any one of an outer crown surface of the crown, a piston ring groove in the crown, and / or the crown includes a steel H11 alloy and / or a steel H13 alloy. A steel H11 or H13 material is applied using any technique, such as piston crown coating / cladding, molten covering, powder cladding, welding on the outer crown surface of the crown, and / or included in the crown and / or skirt of the monolithic piston. The steel H11 or H13 material is applied by additive manufacturing items, with coating, barrier build-up welding, or other surface modifications to facilitate attachment to the piston body. Application of the steel H11 or H13 material with heat treatment to at least the piston crown forms a high performance piston with high temperature oxidation resistance.

Description

[0001] Cross-reference to related applications:

[0002] This application claims the benefit of the filing date of U.S. Provisional Application No. 63 / 637,492, filed April 23, 2024, which is incorporated herein by reference.

[0003] Government licensing rights

[0004] This invention was made with government support under CRADA No. NFE-19-07668 between Cummins, Inc. and UT-Battelle, LLC, the management and operating contractor for Oak Ridge National Laboratory. The government has certain rights in this invention. Technical Field

[0005] The present application generally relates to a piston for an internal combustion engine and, more particularly, to at least one piston crown and, in some embodiments, a piston skirt comprising steel H11 or H13. Background Art

[0006] Pistons for light power density applications can be made of aluminum or aluminum alloy materials, which are cheaper than other materials, but have lower temperature limits than pistons made of other materials. Pistons for higher power density applications need to have higher heat resistance because the temperatures in the combustion zone are higher than in light power density applications. Many pistons in these higher power density applications are made of low alloy steel, such as 4140 alloy, which includes low alloy steel or its variants containing chromium, molybdenum and manganese. Some pistons used in higher power density applications have a crown made of low alloy steel, which is assembled with a piston skirt or body made of micro-alloyed steel. For engines with higher power density, these crowns lack sufficient high temperature strength and high temperature oxidation resistance.

[0007] Pistons used in higher power density applications are often designed with piston cooling passages to reduce piston crown temperatures through forced convection cooling. During operation, cooling oil is contained in or injected into the piston cooling passages to reduce the temperature of the surrounding metal body. However, oil deposits often accumulate on the inner walls, thereby restricting the piston cooling passages. As oil deposits accumulate, the cooling efficiency of the oil circulating therein decreases. These oil deposits (also known as oil coking) in the piston cooling passages are often associated with high thermal loads, which can lead to piston failure due to the piston's poor thermal conductivity and increased thermal stresses.

[0008] Therefore, further contributions are needed in this area of ​​technology to improve the durability of pistons. Summary of the Invention

[0009] A piston for an internal combustion engine includes a piston body having a crown connected to or integral with a skirt. In some embodiments, at least the crown of the piston includes a steel H11 and / or a steel H13 alloy. The steel H11 alloy includes chromium, molybdenum, vanadium, and iron. The steel H13 alloy includes carbon, chromium, molybdenum, vanadium, iron, and lesser amounts of other alloying elements such as silicon and manganese. In some embodiments, the skirt includes a steel H11 and / or a steel H13 alloy.

[0010] In one embodiment, the steel H11 and / or H13 material is a piston crown coating, cladding, or cladding layer applied to a crown surface of the crown. In another embodiment, the steel H11 and / or H13 material is welded on a crown surface of the crown. The steel H11 and / or H13 can be a fusion cladding, cladding, powder cladding, and / or welded on the crown surface.

[0011] In another embodiment, the steel H11 and / or H13 material is used to form or manufacture a monobloc piston including a crown and a skirt at least partially formed from the steel H11 and / or H13 material.

[0012] A piston including a steel H11 and / or H13 material for at least a piston crown can produce a high performance piston that is resistant to high temperature oxidation. A piston including a steel H11 and / or H13 material for at least a piston crown provides a higher power density engine for diesel and alternative fuels.

[0013] Related methods for manufacturing a piston including a piston body having a crown connected to or integral with a skirt, wherein a steel H11 and / or a steel H13 alloy is applied to at least the crown, and in some embodiments, to the skirt as well. In some embodiments, the steel H11 and / or steel H13 alloy is used to manufacture the crown and / or skirt of the piston body.

[0014] This summary is provided to introduce some concepts of the following description in illustrative embodiments. This summary is neither intended to identify key or essential features of the claimed subject matter nor is it used to limit or BRIEF DESCRIPTION OF DRAWINGS

[0015] The concepts described herein are illustrated by way of example and not by way of limitation in the appended figures. For simplicity and clarity of illustration, the drawing figures depicted in the illustrative embodiments can not be to scale. Where considered appropriate, reference labels have been repeated among the figures for indicating corresponding or analogous elements.

[0016] Figure 1 is a side perspective view of an exemplary piston of the present disclosure; and

[0017] Figure 2 is Figure 1 a cross-sectional view of an exemplary piston. DETAILED DESCRIPTION

[0018] For the purposes of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the application is intended by this specification of embodiments, and that alterations and further modifications of the illustrated embodiments, and any further applications of the principles of the application as illustrated herein are contemplated as would normally occur to one skilled in the relevant art.

[0019] Reference is now made to Figure 1 and Figure 2 illustrate the present application, which is an exemplary piston for use in high temperature and / or high pressure environments, such as in internal combustion engines. While exemplary pistons are illustrated in Figure 1 and Figure 2 , the exemplary components illustrated in the figures are not intended to be limiting. Indeed, additional or alternative components and / or embodiments can be used.

[0020] In this exemplary embodiment, the piston 100 includes a crown 114 and a skirt 116. In one or more embodiments, the crown 114 can be attached to, fixed to, or manufactured with the skirt 116. For example, in one or more embodiments, the crown 114 can be welded to the skirt 116. In some other embodiments, the crown 114 can be manufactured in a mold that is also used to manufacture the skirt 116.

[0021] The piston 100 includes a generally cylindrical sidewall 118 that extends along the longitudinal axis 112 from an end 143 of the piston 100 to a first end 121 of the skirt 116 and from the first end 121 to a second end 122 of the skirt 116. The second end 122 of the skirt 116 is configured to allow a connecting rod to engage with the piston 100. The skirt 116 defines a wristpin bore in which a wristpin (not shown) is received and retained to allow a connecting rod to engage with the wristpin. The outer peripheral surface of the crown 114 is formed with a set of ring grooves 164. During engine operation, rings positioned in the piston ring grooves 164 can prevent blow-by and undesirable lubricating oil combustion. In other embodiments, the piston 100 includes a second set of ring grooves proximate the second end 122 of the skirt 116.

[0022] Sidewall 118 is formed with opposing sidewall portions 168 separated from one another by an intermediate sidewall 170. For example, there are two opposing sidewall sections 168 and two opposing sidewalls 170. Portion 168 of sidewall 118 has approximately the same radius as crown 114 relative to longitudinal axis 112. Sidewall 170 minimizes the mass of the piston and the contact area of ​​sidewall 118 against the bore of the cylinder in which the piston is disposed. Sidewall 170 extends longitudinally in sidewall 118 below annular groove 164.

[0023] Crown 114 has an end surface 120 that is shaped to define a combustion chamber with the end surface of an opposed piston in an opposed-piston engine. In one or more embodiments, end surface 120 can be a concave surface, a convex surface, a flat surface, or a combination thereof. End surface 120 includes a recess 135 that extends across crown 114. Recess 135 is configured to align with the position of a corresponding fuel injector along the cylinder bore, wherein piston 100 is disposed at a specific position of piston 100 within the cylinder bore. In other embodiments, piston 100 does not include recess 135.

[0024] In one or more embodiments, the end surface 120 of the crown 114 may be formed from one or more materials. Some exemplary types of materials include steel, steel alloys, titanium, titanium alloys, aluminum, aluminum alloys, and / or silicon, to name a few non-limiting materials. In one or more embodiments, the entire crown 114 may be formed from a material such as steel or a steel alloy. In some embodiments, the entire crown 114 may be formed from a steel H11 alloy and / or a steel H13 alloy. Steel H11 alloy contains carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon and manganese. Steel H13 alloy contains carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon and manganese. Advantageously, the material used to form the end surface 120 of the crown 114 may include aluminum and / or silicon to enhance high-temperature oxidation resistance. In some embodiments, steel H11 and / or steel H13 alloy contains a composition as described in ASTM A681.

[0025] In some embodiments, the steel H11 alloy and / or the steel H13 alloy may include sulfur in the composition, which, if present in too high an amount, may cause fatigue resistance issues for the piston 100. For example, large amounts of sulfur may cause fatigue strength issues, but small or minimal amounts of sulfur may benefit the workability of the piston 100 without compromising any fatigue properties.

[0026] like Figure 2 As shown, skirt 116 includes an inner wall 123 that partially defines cooling passage 132. A peripheral portion of lower surface 136 of crown 114, together with inner wall 123, defines the remainder of cooling passage 132. Cooling passage 132 acts as a conduit for a cooling fluid, such as oil, to cool piston 100.

[0027] The outer crown surface 137 of the crown 114 includes the end surface 120, and the portion of the sidewall 118 spanning between the end surface 120 and the first set of ring grooves 164 can apply steel H11 alloy and / or steel H13 alloy in one or more of the techniques described below by reference. In any embodiment, the first set of ring grooves 164 can also include application of steel H11 alloy and / or steel H13 alloy in one or more of the techniques described below by reference. Steel H11 alloy and / or steel H13 alloy can be applied to the skirt 116 using similar techniques as the outer crown surface 137 or different techniques.

[0028] In one embodiment, steel H11 alloy and / or steel H13 alloy can be applied to the outer crown surface 137 as a piston crown coating 133 on the outer crown surface 137. In one refinement, steel H11 alloy and / or steel H13 alloy is applied as a coating to the outer crown surface 137 by a process such as thermal spraying, with or without a post-coating fusion enhancement process. In one or more embodiments, the outer crown surface 137 includes a thermal barrier coating (TBC) made of steel H11 alloy and / or steel H13 alloy. These treatments to the outer crown surface 137 can form a high-temperature oxidation-resistant high-performance piston.

[0029] In one refinement, steel H11 alloy and / or steel H13 alloy is applied to the outer crown surface 137 as a fusion cladding. In one example, steel H11 alloy and / or steel H13 alloy is applied to the outer crown surface 137 by build-up welding. These treatments to the outer crown surface 137 can form a high-temperature oxidation-resistant high-performance piston.

[0030] In one embodiment, steel H11 alloy and / or steel H13 alloy can be applied to the outer crown surface 137 as a cladding on the outer crown surface 137. In one refinement, steel H11 alloy and / or steel H13 alloy is applied to the outer crown surface 137 by a cladding process, such as by explosive cladding or by hot isostatic powder cladding. In another refinement, steel H11 alloy and / or steel H13 alloy is applied to the outer crown surface 137 as a powder cladding. These treatments to the outer crown surface 137 can form a high-temperature oxidation-resistant high-performance piston.

[0031] In one embodiment, steel H11 alloy and / or steel H13 alloy can be applied to the outer crown surface 137 by welding to the outer crown surface 137. Another type of heat treatment applied to the outer crown surface 137 includes austenitizing and tempering. Industry standard austenitizing temperatures for steel H11 are described in SAE AMS2759 / 1 Table 2B and SAE AMS2759 / 2 Table 2B. One technique to austenitize or harden steel H11 alloy to the outer crown surface 137 includes heating the steel H11 alloy to 500°F (260°C), then step heating to 1500°F (815°C) for 15 minutes, followed by step heating to 1850°F (1010°C) for 30 minutes at temperature. These heat treatments to the outer crown surface 137 can form a high temperature oxidation resistant high performance piston 100.

[0032] Generally, a fine grain size of steel is defined as 5 or finer. One general advantage of a finer grain size is improved toughness of the material. There can also be a Hall-Petch grain size advantage in strength. Some advantages of a coarser grain size are improved creep resistance at high temperatures and improved resistance to recrystallization. Steel H11 alloy and / or steel H13 alloy are specially treated to have a small amount of columnar grains or be single crystal (one grain) to reduce / avoid the disadvantages of grain boundaries at high temperatures. Increasing the grain size has a potential advantage in hardenability; a coarser prior austenite grain has more hardenability and a greater depth of hardening in the material compared to a fine grain material. A thicker section can be fully hardened in a coarse austenite grain structure rather than a fine austenite grain structure. Alternatively, with a coarser austenite grain size in the same section, a milder quench can be used with less distortion and less risk of quench cracking compared to a finer austenite grain size. Increasing the grain size by higher temperature austenitizing allows better solution of alloying elements, higher hardenability of the larger prior austenite grains, and favors finer carbides for better softening resistance in high temperature applications.

[0033] Coarser grain size is a matter of degree. Different types of particles / precipitates have different abilities to control grain size at different temperatures. If the wrong type of particle is used, the grain boundaries can "escape" from the particles at high temperatures and result in a harmful, overly coarse grain size. However, with the right type of particle, the particles can allow a moderately larger grain size to form without forming a harmful, overly coarse grain size.

[0034] In one example, a crown 114 of steel H11 alloy and / or steel H13 alloy is welded / bonded to a skirt 116 of the same or different alloy. In one example, the steel H11 and / or steel H13 alloy crown preform is a forged piece formed by a manufacturing process involving the shaping of a metal alloy using localized compressive forces to form the crown 114. In one example, the steel H11 and / or steel H13 alloy crown preform and / or skirt 116 is an additively manufactured article.

[0035] In one example, the steel H11 and / or steel H13 alloy crown preform is brazed or diffusion bonded to the skirt 116. In one example, the piston 100 including the crown 114 and skirt 116 is made of steel H11 and / or steel H13 alloy.

[0036] In any of the above embodiments, the heat treatment of the steel H11 and / or steel H13 alloy crown 114 provides excellent strength and dimensional stability under peak power operating conditions of the piston 100.

[0037] In any of these manufacturing processes, the outer crown surface 137 and, in some embodiments, the piston ring groove 164 are surface treated with steel H11 alloy and / or steel H13 alloy.

[0038] In one example, the layer thickness of the applied steel H11 and / or steel H13 alloy layer is optimized to minimize the risk of piston oil gallery temperature and oil coking in the cooling gallery 132.

[0039] In one example, the crown 114 of steel H11 and / or steel H13 alloy is treated with a coating, a barrier layer overlay, and / or other surface modification to facilitate joining to the skirt 116. In one example, the skirt 116 is treated with a coating, a barrier layer overlay, and / or other surface modification to facilitate joining to the crown 114 of steel H11 and / or steel H13 alloy and / or application of a crown alloy surface treatment. A barrier layer overlay is the overlaying of a highly weldable material on a challenging weld material to facilitate easy welding to the butter layer later with little risk of problems with the underlying challenging weld material.

[0040] It will be apparent from the drawings and text presented above that various aspects of the present disclosure can be contemplated.

[0041] Various aspects of the present application are contemplated. According to one aspect, a piston for an internal combustion engine, the piston comprising: a piston body having a crown adjacent to a skirt, wherein the crown comprises an outer crown surface, wherein the outer crown surface comprises steel H11 alloy and / or steel H13 alloy for enhanced high temperature oxidation resistance of at least the crown.

[0042] In one embodiment, wherein the steel H11 alloy and / or the steel H13 alloy comprises aluminum and / or silicon.

[0043] In one embodiment, wherein the steel H11 alloy comprises one or more of carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon and manganese.

[0044] In one embodiment, wherein the steel H13 alloy comprises one or more of carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon, sulfur, or manganese.

[0045] In one embodiment, wherein the skirt comprises the steel H11 alloy and / or the steel H13 alloy.

[0046] In one embodiment, wherein the crown and the skirt are monolithic.

[0047] In one embodiment, wherein the piston is a high-temperature oxidation-resistant high-performance piston.

[0048] In one embodiment, wherein the internal combustion engine is a high-power density engine.

[0049] In one embodiment, wherein the crown comprises the steel H11 alloy and / or the steel H13 alloy.

[0050] In one embodiment, wherein the crown includes a set of ring grooves, the ring grooves comprising the steel H11 alloy and / or the steel H13 alloy.

[0051] In one embodiment, wherein the skirt is made of a different alloy than the crown.

[0052] According to another aspect, a method of manufacturing a piston for an internal combustion engine, the method comprising: providing a piston having a piston body, the piston body including a crown adjacent to a skirt, wherein the crown includes an outer crown surface; and applying a steel H11 alloy and / or a steel H13 alloy to the outer crown surface.

[0053] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes a cladding process, the cladding process including explosive cladding, hot isostatic powder cladding, or powder cladding to form a cladding layer.

[0054] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes thermal spraying the steel H11 alloy and / or the steel H13 alloy to form a crown coating, a blanket layer, or a fused blanket layer.

[0055] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes welding the steel H11 alloy and / or the steel H13 alloy to the outer crown surface of the crown.

[0056] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes applying a heat treatment temperature to the steel H11 alloy and / or the steel H13 alloy that is higher than 260°C, then heating the steel H11 alloy and / or the steel H13 alloy to 816°C for 15 minutes.

[0057] In one embodiment, further comprising: after heating to 816°C, then heating the steel H11 alloy and / or the steel H13 alloy to 1010°C for 30 minutes.

[0058] In one embodiment, wherein the skirt is made of a different alloy than the crown.

[0059] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes diffusion bonding the crown to the skirt.

[0060] In one embodiment, wherein applying the steel H11 alloy and / or the steel H13 alloy includes an additive manufacturing article and / or an additive manufacturing process application of the steel H11 alloy and / or the steel H13 alloy.

[0061] In the foregoing description, certain related terms, such as "up", "down", "upper", "lower", "horizontal", "vertical", "left", "right", "proximal", "distal", and the like, can be used. These terms are used in relation to the orientation of the objects described, as appropriate, to provide some clarity of description. These terms are not intended to imply absolute relationships, positions, and / or orientations. For example, an "upper" surface with respect to an object can simply become a "lower" surface by turning the object over. Nonetheless, the object is still the same object.

[0062] References throughout this specification to "one embodiment", "an embodiment", or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearances of the phrases "in one embodiment", "in an embodiment", and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term "embodiment" does not necessarily refer to the same embodiment, although it can. The terms "an embodiment", "one embodiment", and "some embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure, but it does not mean that the feature, structure, or characteristic is included in all embodiments.

[0063] The described features, structures, advantages, and / or characteristics of the subject disclosure can be combined in any suitable manner in one or more embodiments and / or implementations. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the subject disclosure. One skilled in the relevant art will recognize, however, that the subject disclosure can be practiced without one or more of the specific features, details, components, materials, and / or methods described herein. In some instances, the benefits of the present disclosure can be practiced without some of the specific features, details, components, materials, and / or methods described herein. In other instances, additional features and advantages can be recognized in connection with the embodiments and / or implementations described herein. Further, in some instances, well-known structures, materials, or operations have not been described in detail in order to avoid obscuring aspects of the subject disclosure. The features and advantages of the subject disclosure will become more apparent from the following description and accompanying claims, or can be learned by practice of the subject matter as set forth hereinafter.

[0064] The subject matter can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the application is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A piston for an internal combustion engine, the piston comprising: a piston body having a crown adjacent to a skirt, wherein the crown comprises an outer crown surface, wherein the outer crown surface includes a steel H11 alloy and / or a steel H13 alloy for enhanced high temperature oxidation resistance of at least the crown.

2. The piston of claim 1, wherein the steel H11 alloy and / or the steel H13 alloy includes aluminum and / or silicon.

3. The piston of claim 1, wherein the steel H11 alloy includes one or more of carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon and manganese.

4. The piston of claim 1, wherein the steel H13 alloy includes one or more of carbon, chromium, molybdenum, vanadium, iron, and at least one of silicon, sulfur, or manganese.

5. The piston of claim 1, wherein the skirt includes the steel H11 alloy and / or the steel H13 alloy.

6. The piston of claim 1, wherein the crown and the skirt are monolithic.

7. The piston of claim 1, wherein the piston is a high performance piston that is high temperature oxidation resistant.

8. The piston of claim 1, wherein the internal combustion engine is a high power density engine.

9. The piston of claim 1, wherein the crown includes the steel H11 alloy and / or the steel H13 alloy.

10. The piston of claim 9, wherein the crown includes a set of ring grooves that include the steel H11 alloy and / or the steel H13 alloy.

11. The piston of claim 1, wherein the skirt is made of a different alloy than the crown.

12. A method of manufacturing a piston for an internal combustion engine, the method comprising: providing a piston having a piston body including a crown adjacent to a skirt, wherein the crown includes an outer crown surface; and applying a steel H11 alloy and / or a steel H13 alloy to the outer crown surface.

13. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy includes a cladding process including explosive cladding, hot isostatic powder cladding, or powder cladding to form a cladding layer.

14. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy includes thermal spraying the steel H11 alloy and / or the steel H13 alloy to form a crown coating, a blanket, or a fusion blanket.

15. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy includes welding the steel H11 alloy and / or the steel H13 alloy to the outer crown surface of the crown.

16. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy includes applying a heat treatment temperature of the steel H11 alloy and / or the steel H13 alloy above 260°C, and then heating the steel H11 alloy and / or the steel H13 alloy to 816°C for 15 minutes.

17. The method of claim 16, further comprising: after heating to 1500°F, then heating the steel H11 alloy and / or the steel H13 alloy to 1010°C for 30 minutes.

18. The method of claim 12, wherein the skirt is made of a different alloy than the crown.

19. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy comprises diffusion bonding the crown to the skirt.

20. The method of claim 12, wherein applying the steel H11 alloy and / or the steel H13 alloy comprises an additive manufacturing project and / or an additive manufacturing process application of the steel H11 alloy and / or the steel H13 alloy.

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